It is the distance from the centerline of the crankshaft in the block,(center of main cap) to the deck where the head bolts on. If your block has been decked or milled you will not get the correct measurement but it will be close.
Hello...OK..I just measured and I get 10"..From the center for the crank shaft to the top of the block..If this makes sense, the angle of measurement was 6:00 o'clock to 2:00 o'clock,due to the angle of the deck..
Hope this helps
Duane
Hello..I have a 1935 Tudor Ford Slant back Sedan...My hobbies are Stromberg 97s and intakes manifolds..
Check out the website "hemi.com" . If you go to the early Hemi section, you will find that the deck height for the 241/270 is listed as 9.29 inches. I belive the dimensions listed on this site are accurate. Hope this helps.